Improvement in ports for steam-engine cylinders



3 Sheets--Sheet 1.

W. C. CHURCH.

YPorts for Steam-Engine Cylinders.

No.l66,849, y PatentedAugALm um mnu f 3 Sheets--Sheet 2.

yl inde rs.

Patented Aug. 17,1875.

N. PETERS, PHOTO UTHOGRA 3'Sheets--Sheet 3.

W. C. CHURCH. Ports for Steam-Engine Cylinders.

Patented Aug. 17.1'87'5;

UNITED STATES PATENT OFFICE.,

WALTER C. CHURCH, OF WESTMINSTER, ENGLAND.

IMPROVEMENT IN PORTS FOR STEAM-ENGINE CYLINDERS.

Specification forming part of Letters Patent No. 166,849, dated August 17, 1875 application iiled July 12,1875.

To all whom it may concern:

Be it known that I, WALTER GHARLEs CHURCH, of S Victoria Chambers, Victoria Street, in the city of Westminster, England, have invented Improvements in the Cylinders `of Steam, Air, Gas, or Hydraulic Motive- Iower Engines or Steam-Hammers, ofwhich the followingis a specification i My invention (for which aBritish patent,No. 563, was issued April 19, 1872,) relates lnore particularly to the construction ofthe port-faces of steam, air, gas, or hydraulic motive-power cylinders, fitted with the peculiar circular slidevalve in respect of which I made application for a patent March 2, 1874, but is also applicable with circular slide-valves of other constructions, and it has for its object enabling the length and Width of the steam -passages to be reduced, While increasing the length of the port for the lead.

In order to effect these objects I make the valve ports in the cylinder of a peculiarlycurved form, as hereinafter described, and illustrated on the accompanying drawings.

Figure l represents a plan, drawn to a reduced scale, of a cylinder constructed with my improved steam and exhaust ports. Fig. 2 is a corresponding longitudinal section of a portion of the cylinder with the steam and exhaust ports. Fig. 3 represents a plan of my improved ports adapted to a twelve-inch circular slide-valve.

Similar letters indicate corresponding parts in all the igures.

The valve-ports, in lieu of bein g rectangular, are of the peculiar curvilinear form shown in Figs. 1 and 3 of my drawings. The ports are also angled or inclined below the port-face to suit their curvilinear form, as shown bythe dotted lines c iu Fig. 2, which angle or inclination extends round the exhaust side, across the ends of the steam-ports, and round to the lpassages to the cylinder, as shown at c in Fig.

3. These last mentioned dotted lines also show the clearance requisite below the portface for the tool to clear in slotting them out, as each arc can be slotted under a radial slottii'ig-machine in small-sized cylinders.

This form of steam-porta enables the steampassages to the cylinders to be shortened and reduced in width, as shown in plan in Figs. 1

and 3, while at the same time a larger area and uniform lead for admission onto the piston are obtained throughout the entire length of the port.

In the plan, Fig. 3, I have also shown the method of setting out the various curves requisite for a valve twelve inches diameter, which is as follows,reference being hadto thetigured dimensions on the said plan First, describe the circle of the valve C of the diameter fixed upon, which, as shown in the drawing, Fig. 3, is twelve inches diameter, or six inches radius. Within this circle, mark oft' on each side, from the circumferential line on the centerline, the outside lap and the Width ot' the steam-port a, which are, respectively, three-fourths of an inch and one inch, as shown in the plan, Fig. 3. This gives the Width of valve-face, namely, one and three fourths inch. This dimension will vary according to the outside lap of the valve and the width of the steamport a, also of the inside lap, if adopted. The diameter of the exhaust-opening in the valve is found by subtracting the Width ofthe valveface on each side from the diameter of the valve C, namely, twelve inches minus three and a half inches, which leaves eight and a half inches for the diameter of the exhaustopening in the valve C. This dimension will also vary according to the inside lap of the valve adopted.

The radius for the outer edges of the portface is the same as that of the valve, namely, six inches, and the Width from the outside of the port-face t-o the outer arc of the steamport a is one and seven-eighths of an inch. This dimension can be varied according to the travel and outside lap of the valve or the length of the port-face decided upon. The radius for the outer arc or curve of the steamport a is about one-sixteenth of an inch greater than that ot' the valve-face C, and'is therefore about six and one-sixteenth inches, as shown in the drawing, Fig. 3, giving a uniform opening of one-eighth of an inch for the entirey length of the arc of the steam-port a, which is fourteen inches long, and allowing the port to commence opening at the two extremities of the arc or curve in lieu of 011 the center line. The same result occurs on the exhausting side of the steam-port. This dimension also varies according to the vlead or opening decided upon. When a greater amount of uniform lead or openin g is required the radius of thel outer arc of the steam-port a will increase in a greater proportion to the radius of the v-.ilveface C, as, the valve-face being circular, its motion causes the steam-port a to open more quickly on the center line while traveling over the port-face, thereby requiring the outer arc of the steam-port a to be struck with a greater radius than that of the valve C, thus giving a greater opening with a uniform lead on the entire length of the arc of the steamport a, and thereby accomplishing, by increasing the radius of the outer arc, any amount of uniform lead or port-opening required.

' The width of the steam-port a on the center line is one inch, and the radius of the arc of the inside of the steam-port t is about onesixteenth of aninch less than the radius of the exhaust-opening in the valve C, namely, about four and three-sixteenths inches, which produces a uniform opening throughout the entire length of the arc on the exhaust side of the steam-port a, and as the valve c travels over the steam-port a, and opens the exhaust side thereof at the same time, the length of the exhaust-arc of the valve C increases in such a rapid manner over the inner arc of the steam-port a as to allow the steam to escape freely from the cylinder. ing in the valve C being of a circular form, it opens more quickly on the center line, and therefore the arc on the exhaust side of the steam-port a is struck with a less radius than that of the valve C, which is tour and one-half inches, as shown in Fig. 3. This dimension will also Vary by reducing the radius of the inner arc of the exhausting side of the steamport according to the inside lap of the valve and the amount of uniform opening required.

The width ofthe bar between the steam and exhaust ports on the center line is one and one-eighth inch, and the radius of the arcof the exhaust-port b is the same as that of the exhaust-opening in the valve C, namely, four and one-fourth inches. This dimension will also vary according to the inside lapA of the valve adopted; and when the valve G works expansively, only opening the steam-port a on the center line three-eighths of an inch, the inside of the circular exhaust-opening in the valve C Will be Hush with the arc or curve of the exhaust-port b, (see plan, Fig. 3,) thereby pro. ducing a uniformity of wear on the surfaces, whether working in full throw or expansively. This can also be Varied, so that when the valve just opens on the lead the same result can be obtained.

The practical rule' adopted for giving vadditional outside lap on ordinary rectangular slide-valves over the steam-ports increases the width of the valve-face, thereby giving an increased area on the backy of the valve exposed to the pressure of steam in the steamchest, tending to press it to the port-face; but

The exhaust-openof the valve may be. increased without increasing the area on the back of the valve acted upon by the pressure of steam in the steamchest by bringing the outer curves or arcs of the steam-ports a a closer together on the center line, leaving,vnevert-heless, a suflicient area between the two curves or arcs of the exhaust-port b for the steam to escape freely from the cylinder, also leaving a uniform opening throughout the entire length of the curve or arc of the steam-port a, (which is fourteen inches lon g, as hereinbefore described, and illustrated by Figs. 1 and 3 5) hence the superiority of my method for setting out the ports on the port-face for circular valves will be obvious.

Although I have given a twelve-inch -valve las an example, it is obvious that the diameter may be varied, as a greater or less area of port-opening or lead is required for yadmission onto the piston, and therefore the advantages to be gained by the adoption of this form of port-face in cylinders of large diameter is the dispensing with the double or gridiron portface, as by my improved Inode of port-face I can give all the area'of port-opening necessary for the admission of steam onto the piston, as well as a suiiicient area to the exhaust, thereby saving a large amount of steam in charging the passages for each stroke of the engine.

In the case of single-acting cylinders-that is to say, cylinders in which the motive fluid acts upon one side only of the piston or ramone lsteam-port and one exhaust-port only will be required, which will be constructed upon the principles hereinbefore described. When, however, the invention is applied to cylinders requiring two port-faces, in order to shorten the steam-passages into the cylinder, the ports are arranged in a manner similar to thosel for single-acting cylinders, but two sets are employed, viz., a steam-port and exhaust-port for each side of the piston.

I claim- 1. A cylinder provided with a port or ports, t a, curved and expanding in width from the center to the ends, all as and for the purpose set forth.

2. The combination of the curved port or ports a with the exhaust-port b, widest on its transverse diameter,-as set forth.

vIn witness whereof I have signed luy name to this specification in the presence of two subscribing Witnesses.

W. C. CHURCH.

Witnesses:

OHAs. MILLS,

4:7 Lt'ucolns Innllelds, London. FREDK. C. DYER,

47 Lncolns Ian Fields, London. 

